This invention relates to the preparation of an aqueous solution of an alkali metal borohydride, an alkali metal hydroxide, and an anionic polymer. It relates also to the use of said solution in the removal of metal ions from metal-bearing wastewaters.
The use of sodium borohydride to remove a dissolved metal ion from wastewater as a reduced precipitate in conjunction with the use of sodium aluminate and a commercial flocculent to coagulate the precipitate is taught in U.S. Pat. No. 4,975,203. Before the time of the invention taught in said '203 patent, the borohydride and aluminate were added sequentially. Up until the time of this invention, the flocculent has always been added to the wastewater after the borohydride and aluminate treatment.